JP2021115884A - Four-wheel drive vehicle - Google Patents

Abstract

To provide a four-wheel drive vehicle that is able to enhance traveling stability at the point of the occurrence of an accident.SOLUTION: A four-wheel drive vehicles 1, 1A each include a drive force transmission system 10 that can distribute a drive force of an engine 11, serving as a drive source, to front wheels 191, 192 and rear wheels 193, 194, and the drive force transmission system 10 is controlled by a control device 3. The control device 3 can acquire, from a communication device 4, information on a forward road condition in an advancing direction. When the acquired information indicates an occurrence of an accident, the control device causes the drive force transmission system 10 to perform an operation of equalizing the proportions of distribution of drive force to the front wheels 191, 192 and the rear wheels 193, 194 before reaching the point of the occurrence of the accident, or a preparation operation therefor.SELECTED DRAWING: Figure 5

Description

The present invention relates to a four-wheel drive vehicle in which the driving force distribution ratio to the front wheels and the rear wheels is controlled by a control device.

Conventionally, some vehicles that distribute the driving force of a driving source such as an engine to a plurality of wheels have a variable driving force distribution ratio to a plurality of wheels by adjusting the clutch engagement force (for example, a patent). Reference 1).

The vehicle driving force distribution device described in Patent Document 1 has driver operation information, vehicle behavior information, or information from a car navigation device in order to improve responsiveness when changing the driving force distribution ratio. It is provided with a distribution control prediction means for predicting the distribution control of the driving force based on the above, and a distribution control preparation means for preparing for the distribution control of the driving force when the prediction by the distribution control prediction means is received. The distribution control predicting means is used, for example, when a curve is detected based on information from a car navigation device, when the steering is turned, when the steering torque is increased, when the blinker is turned on, or when the yaw rate is increased. Predict the distribution control of driving force. When the distribution control preparatory means receives the prediction by the distribution control prediction means, the distribution control preparatory means applies a pressure close to the preload pressure of the return spring that urges the hydraulic piston in the return direction to the hydraulic piston that presses the clutch.

JP-A-2008-261453 (see claims 1-3, paragraphs [0015], [0054], [0059], [0060], [0063]).

By the way, a four-wheel drive state in which the driving force of the driving source is distributed to the front wheels and the rear wheels and a two-wheel driving state in which the driving force of the driving source is distributed to only one of the front wheels and the rear wheels can be switched. In a vehicle, the driving state is set to a two-wheel drive state during steady driving to suppress deterioration of fuel efficiency, and for example, when driving on a low μ road, the driving state can be switched to a four-wheel drive state to improve driving stability. However, in a situation where the road condition suddenly changes, the switching from the two-wheel drive state to the four-wheel drive state may not be in time, and the running stability may be temporarily deteriorated.

For example, when an accident occurs on the road, liquids such as engine oil and transmission oil and various debris such as damaged window glass and bumpers may be scattered on the road surface, making the road surface at the accident occurrence point slippery. .. Then, if the vehicle enters such an accident occurrence point in the two-wheel drive state, the running stability tends to decrease as compared with the case in the four-wheel drive state.

Therefore, an object of the present invention is to provide a four-wheel drive vehicle capable of improving running stability at an accident occurrence point.

The present invention is a four-wheel drive vehicle including a driving force transmission system capable of distributing the driving force of a driving source to front wheels and rear wheels in order to achieve the above object, and the driving force transmission system is controlled by a control device. Therefore, the control device can acquire information on the road condition ahead in the traveling direction, and when the acquired information indicates the occurrence of an accident, the front wheels and the rear wheels are before reaching the point where the accident occurs. Provided is a four-wheel drive vehicle capable of causing the driving force transmission system to perform an operation of equalizing the driving force distribution ratio to the vehicle or a preparatory operation thereof.

According to the four-wheel drive vehicle according to the present invention, it is possible to improve the running stability at the accident occurrence point.

It is a schematic block diagram which shows the structural example of the four-wheel drive vehicle which concerns on 1st Embodiment. It is sectional drawing which shows the structural example of the driving force transmission device. It is a schematic block diagram which shows the schematic block block example of a control device and its surroundings. (A) is a schematic diagram showing a configuration example of a wireless access network of an intelligent transportation system. (B) shows the state of the collision accident that occurred at the point A shown in (a). It is a flowchart which shows the specific example of the process which a control part executes. It is a schematic block diagram which shows the structural example of the four-wheel drive vehicle which concerns on 2nd Embodiment.

[First Embodiment]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 5. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect.

FIG. 1 is a schematic configuration diagram showing a schematic configuration example of a four-wheel drive vehicle according to the first embodiment of the present invention.

As shown in FIG. 1, the four-wheel drive vehicle 1 includes a driving force transmission system 10 that can distribute the driving force of the engine 11 as a driving source to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194. The force transmission system 10 is controlled by the control device 3. The rotation of the crankshaft, which is the output shaft of the engine 11, is changed by the transmission 12. Hereinafter, the four-wheel drive vehicle 1 may be referred to as the own vehicle 1.

The driving force transmission system 10 has a four-wheel drive state in which the driving force of the engine 11 is distributed to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194, and the driving force of the engine 11 is distributed only to the left and right front wheels 191 and 192. It is possible to switch between the two-wheel drive state. Wheel speed sensors 101 to 104 are respectively arranged on the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194, respectively. An electric motor may be used as the drive source, or the engine and the electric motor may be combined as the drive source.

The driving force transmission system 10 includes a front differential 13 and a transfer 14 arranged on the front wheel side, a propeller shaft 15 for transmitting a driving force in the front-rear direction of the vehicle, a rear differential 16 arranged on the rear wheel side, and a rear differential 16. It is arranged between the pinion gear shaft 160 that transmits the driving force to the left and right front wheel side drive shafts 171, 172, the left and right rear wheel side drive shafts 181, 182, and the propeller shaft 15 and the pinion gear shaft 160. It has a driving force transmission device 2.

The driving force transmission device 2 is controlled by the control device 3 and transmits a driving force corresponding to the current supplied from the control device 3 from the propeller shaft 15 to the pinion gear shaft 160. The control device 3 includes wheel speed information indicating the rotation speeds of the left and right front wheels 191 and 192 and left and right rear wheels 193 and 194 detected by the wheel speed sensors 101 to 104, and the accelerator pedal 111 detected by the accelerator pedal sensor 105. It is possible to acquire information on the accelerator opening degree indicating the amount of operation and information on the steering angle indicating the rotation angle of the steering wheel 112 detected by the steering angle sensor 106. The information on the wheel speed, the accelerator opening degree, and the steering angle is an example of a state quantity indicating the vehicle state of the four-wheel drive vehicle 1, and the control device 3 controls the driving force transmission system 10 based on these state quantities. Then, the driving force distribution ratio to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194 is adjusted.

The driving force of the engine 11 is transmitted to the left and right front wheels 191 and 192 via the transmission 12, the front differential 13, and the drive shafts 171 and 172 on the left and right front wheels. The front differential 13 is a pair of side gears 131 and 131 connected to the drive shafts 171 and 172 on the left and right front wheels so as not to rotate relative to each other, and a pair of pinion gears that mesh with the pair of side gears 131 and 131 with their gear axes orthogonal to each other. It has 132, 132, a pinion gear shaft 133 that supports a pair of pinion gears 132, 132, and a front differential case 134 that accommodates them.

The transfer 14 has a ring gear 141 fixed to the front differential case 134 and a pinion gear 142 connected to the front end of the propeller shaft 15 and meshing with the ring gear 141, and transmits a driving force to the propeller shaft 15. The rear end of the propeller shaft 15 on the vehicle rear side is connected to the housing 20 which is an input rotating member of the driving force transmission device 2. The driving force transmission device 2 has an inner shaft 23 as an output rotating member arranged so as to be relatively rotatable with the housing 20, and a pinion gear shaft 160 is connected to the inner shaft 23 so as to be relatively non-rotatable. The details of the driving force transmission device 2 will be described later.

The rear differential 16 is a pair of side gears 161, 161 connected to the left and right rear wheel side drive shafts 181, 182 so as not to rotate relative to each other, and a pair of side gears 161, 161 that are engaged with the gear shafts orthogonal to each other. It has a pinion gear 162, 162, a pinion gear shaft 163 that supports a pair of pinion gears 162, 162, a rear differential case 164 that accommodates the pinion gears 162, and a ring gear 165 that is fixed to the rear differential case 164 and is a hypoid gear that meshes with the pinion gear shaft 160. ing.

(Structure of driving force transmission device)
FIG. 2 is a cross-sectional view showing a configuration example of the driving force transmission device 2. In FIG. 2, the upper side of the rotation axis O shows the operating state (torque transmission state) of the driving force transmission device 2, and the lower side shows the non-operating state (torque non-transmission state) of the driving force transmission device 2. Hereinafter, the direction parallel to the rotation axis O is referred to as an axial direction.

The driving force transmission device 2 is formed between a housing 20 composed of a front housing 21 and a rear housing 22, a tubular inner shaft 23 supported so as to be relatively rotatable coaxially with the housing 20, and between the housing 20 and the inner shaft 23. It has a main clutch 24 arranged in, a cam mechanism 25 that generates a thrust force that presses the main clutch 24, and an electromagnetic clutch mechanism 26 that operates the cam mechanism 25 by receiving a current supply from the control device 3. It is configured. Lubricating oil (not shown) is sealed inside the housing 20.

The front housing 21 has a bottomed cylindrical shape having a cylindrical tubular portion 21a and a bottom portion 21b integrally, and a propeller shaft 15 (see FIG. 1) is connected to the bottom portion 21b via, for example, a cross joint. A plurality of outer spline protrusions 211 extending in the axial direction are formed on the inner surface of the tubular portion 21a. The rear housing 22 is partially formed of a ring-shaped non-magnetic material 221 in the radial direction, and rotates integrally with the front housing 21.

The inner shaft 23 is supported on the inner circumference of the housing 20 by bearings 271,272, and has a plurality of inner spline protrusions 231 extending in the axial direction on the outer peripheral surface. Further, on the inner surface of one end of the inner shaft 23, a spline fitting portion 232 in which one end of the pinion gear shaft 160 (see FIG. 1) is fitted so as not to rotate relative to each other is formed.

The main clutch 24 includes a plurality of main outer clutch plates 241 and a plurality of main inner clutch plates 242 arranged alternately along the axial direction. The outer peripheral end of the main outer clutch plate 241 is engaged with the outer spline protrusion 211 of the front housing 21. The end of the main inner clutch plate 242 on the inner peripheral side is engaged with the inner spline protrusion 231 of the inner shaft 23.

The cam mechanism 25 is arranged between the pilot cam 251 that receives the rotational force of the housing 20 via the electromagnetic clutch mechanism 26, the main cam 252 that presses the main clutch 24 in the axial direction, and the pilot cam 251 and the main cam 252. It is configured to have a plurality of spherical cam balls 253. A plurality of cam grooves 251a and 252a whose axial depths change along the circumferential direction are formed on the facing surfaces of the pilot cam 251 and the main cam 252, respectively, and between these cam grooves 251a and 252a. The cam ball 253 is arranged. A thrust bearing 254 is arranged between the pilot cam 251 and the rear housing 22. The main cam 252 is engaged with the inner spline protrusion 231 of the inner shaft 23 so as to be relatively non-rotatable and axially movable, and is urged toward the pilot cam 251 by a disc spring 255 as a return spring.

The electromagnetic clutch mechanism 26 includes an armature 260, a plurality of pilot outer clutch plates 261 and a plurality of pilot inner clutch plates 262, and an electromagnetic coil 263. The electromagnetic coil 263 is held by a yoke 264 supported by a rear housing 22 by a bearing 273. A current from the control device 3 is supplied to the electromagnetic coil 263 via the electric wire 265.

The plurality of pilot outer clutch plates 261 and pilot inner clutch plates 262 are alternately arranged along the axial direction between the armature 260 and the rear housing 22. The outer peripheral end of the pilot outer clutch plate 261 and the armature 260 is engaged with the outer spline protrusion 211 of the front housing 21. The end of the pilot inner clutch plate 262 on the inner peripheral side is engaged with the pilot cam 251.

The control device 3 can adjust the driving force transmitted from the driving force transmitting device 2 to the left and right rear wheels 193 and 194 by increasing or decreasing the current supplied to the electromagnetic coil 263. In the driving force transmission device 2, magnetic flux is generated in the magnetic path G by the current supplied to the electromagnetic coil 263, the armature 260 is attracted to the rear housing 22 side, and the pilot outer clutch plate 261 and the pilot inner clutch plate 262 rub against each other. Upon contact, the pilot cam 251 rotates relative to the main cam 252, the cam ball 253 rolls on the cam grooves 251a and 252a, and a thrust force is generated on the main cam 252 to press the main clutch 24. Then, a frictional force is generated between the plurality of main outer clutch plates 241 and the plurality of main inner clutch plates 242, and the driving force is transmitted from the housing 20 to the inner shaft 23.

In the driving force transmission device 2, the electromagnetic clutch mechanism 26 and the cam mechanism 25 are sequentially operated as described above, and a frictional force is generated between the plurality of main outer clutch plates 241 of the main clutch 24 and the plurality of main inner clutch plates 242. Since it is generated, there is a time delay between the time when the current is supplied to the electromagnetic coil 263 and the time when the driving force is transmitted to the left and right rear wheels 193 and 194. Therefore, even if a current is supplied to the electromagnetic coil 263 after one of the left and right front wheels 191 and 192 slips due to a sudden change in road conditions when traveling in a two-wheel drive state, the left and right rear wheels 193 and 194 are driven. It may take, for example, several seconds for the force distribution ratio to increase and the slip to converge, and during this period, the vehicle behavior may become unstable.

In addition, when an accident occurs on the road, liquids such as engine oil and transmission oil and various debris such as damaged window glass and bumpers may be scattered on the road surface, making the road surface at the accident occurrence point slippery. be. Therefore, in the present embodiment, when the control device 3 detects that an accident has occurred in the forward direction in the traveling direction, the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194 are reached before reaching the accident occurrence point. The driving force transmission system 10 is made to perform an operation of equalizing the driving force distribution ratio of the above. Specifically, the current supplied to the electromagnetic coil 263 is increased to increase the driving force distribution ratio to the left and right rear wheels 193 and 194. Hereinafter, the configuration of the control device 3 for this purpose and specific examples of the processing contents will be described in detail.

(Control device configuration)
FIG. 3 is a schematic configuration diagram showing a schematic configuration example of the control device 3 and its surroundings. The four-wheel drive vehicle 1 is equipped with a communication device 4 capable of communicating with an information providing server 50 of Intelligent Transport Systems (ITS), which is a comprehensive information communication system for road traffic. The control device 3 can acquire the information obtained from the information providing server 50 by the communication device 4 via the vehicle-mounted network.

The information providing server 50 stores road information regarding the road conditions of expressways and some general roads provided by, for example, the National Police Agency or the Road Traffic Information Center. The communication device 4 can acquire road information from the information providing server 50 via the core network 51 of the intelligent transportation system and the radio access network 52. The radio access network 52 is constructed by a base station 521 that performs wireless communication.

Specifically, as this wireless communication standard, the wireless access technology (RAT: Radio Access Technology) of 3GPP (Third Generation Partnership Project), which is a standardization project for examining and creating network specifications such as mobile communication, was used. V2X (Vehicle-to-Everything) can be mentioned. Further, the communication standard of the radio access network 52 may be the 4th generation mobile communication system (4G) or the 5th generation mobile communication system (5G).

The control device 3 is an electromagnetic coil 263 via a control unit 30 realized by the CPU (arithmetic processing device) executing a program, a switching element 301 that is PWM-controlled, a flywheel diode 302, and a switching element 301. It has a current detection circuit 303 that detects the current supplied to the device. The switching element 301 is, for example, a MOSFET, and an IG power supply 110 that outputs a power supply voltage when the ignition switch for starting the engine 11 is in the ON state is connected to the drain, and the source is connected to one end of the electromagnetic coil 263. There is.

The control unit 30 calculates a torque command value indicating a driving force to be transmitted to the left and right rear wheels 193, 194 based on information on the wheel speed, accelerator opening, and steering angle. The second torque command value calculation unit 32, the first torque command, which calculates the torque command value indicating the driving force to be transmitted to the left and right rear wheels 193, 194 based on the road information obtained via the communication device 4. The torque command value calculated by the value calculation unit 31 and the torque command value calculated by the second torque command value calculation unit 32 are supplied to the electromagnetic coil 263 of the driving force transmission device 2 according to the larger torque command value. As a current command value calculation unit 33 that calculates a current command value indicating a value of the current to be output, and a current control unit 34 that PWM-controls the switching element 301 so that a current corresponding to the current command value is supplied to the electromagnetic coil 263. Function. Hereinafter, the torque command value calculated by the first torque command value calculation unit 31 is referred to as a first torque command value, and the torque command value calculated by the second torque command value calculation unit 32 is referred to as a second torque command. It is called a value.

The control unit 30 indicates that an accident has occurred in front of the traveling direction based on the information acquired from the communication device 4 when traveling in a two-wheel drive state or when traveling in a state where the driving force distribution ratio to the left and right rear wheels 193 and 194 is small. At this time, the current supplied to the electromagnetic coil 263 is increased before reaching the point where the accident occurs, and the driving force distribution ratio to the left and right rear wheels 193 and 194 is increased. That is, the driving force distribution ratio to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194 is equalized.

FIG. 4A is a schematic diagram showing a configuration example of a wireless access network 52 of an intelligent transportation system. FIG. 4A shows three base stations 521 constituting the radio access network 52 and a plurality of vehicles 6 traveling on the road. The base station 521 performs wireless communication with the vehicle 6 in each communication area.

FIG. 4B shows a state in which a collision accident between vehicles 6 occurs at the point A shown in FIG. 4A, and oil 61 and a plurality of debris 62 are scattered on the road surface. At the point where this accident occurred, an ambulance 7 which is an emergency vehicle is stopped and is carrying out rescue activities. Further, in FIG. 4B, the four-wheel drive vehicle 1 is shown as the own vehicle 1.

Point A, which is the point where the accident occurred, corresponds to the front of the own vehicle 1 in the traveling direction. When the own vehicle 1 passes through the point A while being driven by two wheels, the oil 61 and the debris 62 cause slippage in either the left and right front wheels 191 and 192, and the running stability tends to decrease. Therefore, the vehicle 1 passes through the point A. In that case, it is desirable to change the drive state to a four-wheel drive state.

FIG. 5 is a flowchart showing a specific example of processing executed by the control unit 30 at predetermined control cycles. In the process shown in the flowchart, the control unit 30 first acquires the wheel speed information, the accelerator opening information, and the steering angle information via the vehicle-mounted network (step S1), and the wheel speed is stored in the control map stored in advance. , The accelerator opening degree, and the steering angle are applied to calculate the first command torque (step S2).

Next, the control unit 30 acquires road information regarding the road condition ahead in the traveling direction from the information providing server 50 via the communication device 4 (step S3). Then, it is determined whether the acquired road information includes information indicating the occurrence of an accident (step S4). In step S4, when the road information includes information indicating that the emergency vehicle is stopped in addition to the information directly indicating the occurrence of the accident, the accident occurs at the stop position of the emergency vehicle. Judgment is made assuming that there is. That is, when the information acquired in step S3 includes the information on the stop position of the emergency vehicle, the control unit 30 recognizes that an accident has occurred at that stop position. If the road information acquired from the information providing server 50 includes information indicating the state of the emergency vehicle (moving, rescue, waiting, etc.), the determination in step S4 may be performed in consideration of the information. ..

When the information acquired in step S3 includes information indicating the occurrence of an accident (S4: Yes), the control unit 30 calculates the distance to the accident occurrence point (step S5). Further, the control unit 30 determines whether or not the distance from the current position of the own vehicle 1 to the accident occurrence point is less than the predetermined value (step S6), and when this distance is less than the predetermined value (S6: Yes), the second command torque is set to a predetermined value at which the own vehicle 1 is in the four-wheel drive state (step S7). On the other hand, if the result of the determination in step S4 or S6 is no (No), the control unit 30 sets the second command torque to 0 (zero) (step S8).

The predetermined value in step S7 is, for example, a value (fixed value) of about one-third to one-half of the maximum value of the driving force that can be transmitted to the left and right rear wheels 193 and 194, but the propeller shaft 15 A second command torque may be set as a variable value that changes according to the magnitude of the input torque input to the housing 22 of the driving force transmission device 2. Further, the predetermined value in step S6 is a distance at which the switching from the two-wheel drive state to the four-wheel drive state can be completed by the time the accident occurs, for example, several tens of meters. The predetermined value in step S6 may be changed according to the vehicle speed.

Next, the control unit 30 calculates a current command value according to the larger command torque of the first command torque and the second command torque (step S9), and the current of this current command value is the electromagnetic coil 263. The switching element 301 is PWM-controlled so as to be supplied to (step S10). Specifically, the duty ratio of PWM control is adjusted so that the current value detected by the current detection circuit 303 matches the current command value, and feedback control is performed.

When an accident occurs in front of the traveling direction by the above series of processes, the driving state becomes a four-wheel drive state at least when the own vehicle 1 reaches the accident occurrence point.

(Effect of the first embodiment)
According to the first embodiment described above, even when the accident occurrence point is approached while traveling in the two-wheel drive state, the drive state becomes the four-wheel drive state before reaching the accident occurrence point. Therefore, it is possible to improve the running stability at the accident occurrence point.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic configuration diagram showing a schematic configuration example of the four-wheel drive vehicle 1A according to the present embodiment. Similar to the first embodiment, the four-wheel drive vehicle 1A provides a driving force transmission system 10 capable of distributing the driving force of the engine 11 as a driving source to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194. The driving force transmission system 10 is controlled by the control device 3, but the configuration of the driving force transmission system 10 and the control content of the control device 3 are different from those of the first embodiment.

In the first embodiment, the case where the driving force transmission device 2 is arranged between the propeller shaft 15 and the rear differential 16 has been described, but in the present embodiment, the driving force transmission device 2 is the rear differential 16. A pinion gear 151 that is arranged between one side gear 161 and the drive shaft 181 on the left rear wheel side and meshes with the ring gear 165 of the rear differential 16 is attached to the rear end of the propeller shaft 15 on the vehicle rear side. Further, in the first embodiment, the case where the ring gear 141 of the transfer 14 is fixed to the front differential case 134 and rotates integrally has been described, but in the present embodiment, the transfer 14 has the front differential case 134 and the ring gear 141. A meshing clutch 8 for interrupting the connection is arranged.

Since the configuration of the other four-wheel drive vehicle 1A is the same as that of the first embodiment, the members and the like common to those described in the first embodiment are the same as those attached to FIG. The duplicate description is omitted by adding a reference numeral.

The meshing clutch 8 is arranged on the outer periphery of the first meshing member 81 that rotates integrally with the front differential case 134, the second meshing member 82 that rotates integrally with the ring gear 141, and the first meshing member 81 and the second meshing member 82. A sleeve 83, which is a cylindrical connecting member, and an actuator 84 for moving the sleeve 83 are provided.

The actuator 84 is controlled by the control device 3 to move the sleeve 83 in the axial direction of the first meshing member 81 and the second meshing member 82. When the sleeve 83 moves to one side in the axial direction, the sleeve 83 meshes with the first meshing member 81 and the second meshing member 82, and when the sleeve 83 moves to the other side in the axial direction, the sleeve 83 moves to the second meshing member. It meshes only with 82. When the sleeve 83 meshes with the first meshing member 81 and the second meshing member 82, the driving force of the engine 11 is transmitted to the rear differential 16 via the propeller shaft 15. Of the first meshing member 81 and the second meshing member 82, one meshing member may be movable in the axial direction with respect to the other meshing member. In this case, the driving force of the engine 11 is transmitted to the rear differential 16 via the propeller shaft 15 by engaging the one meshing member with the other meshing member.

One side gear 161 of the rear differential 16 is connected to the housing 20 of the driving force transmission device 2 via an intermediate shaft 166, and rotates integrally with the housing 20. A drive shaft 181 on the left rear wheel side is connected to the inner shaft 23 of the driving force transmission device 2 so as not to rotate relative to each other.

When traveling in a four-wheel drive state, the sleeve 83 of the meshing clutch 8 connects the first meshing member 81 and the second meshing member 82 so that they cannot rotate relative to each other, and the current supplied to the electromagnetic coil 263 of the driving force transmission device 2. The driving force corresponding to the above is transmitted to the left rear wheel 193 via the drive shaft 181 on the left rear wheel side. Further, the differential gear mechanism of the rear differential 16 also transmits a driving force corresponding to the driving force transmitted to the left rear wheel 193 to the right rear wheel 194.

On the other hand, when traveling in the two-wheel drive state, the connection between the first meshing member 81 and the second meshing member 82 in the meshing clutch 8 is released, and the current supplied to the electromagnetic coil 263 of the driving force transmission device 2 is zero. It becomes. As a result, the rotation of the propeller shaft 15 is stopped, and the power loss due to the rotation of the propeller shaft 15, the engagement between the ring gear 141 of the transfer 14 and the pinion gear 142, and the engagement between the ring gear 165 of the rear differential 16 and the pinion gear 151 is suppressed. , Fuel efficiency is improved.

When switching the drive state to the four-wheel drive state when traveling in the two-wheel drive state, the current supplied to the electromagnetic coil 263 of the drive force transmission device 2 is gradually increased to transmit the rotational force of the left rear wheel 193. It is transmitted to the propeller shaft 15 via the device 2 and the rear differential 16, and the propeller shaft 15 is rotated to rotate and synchronize the first meshing member 81 and the second meshing member 82 of the meshing clutch. After that, the actuator 84 is controlled, and the sleeve 83 connects the first meshing member 81 and the second meshing member 82 so that they cannot rotate relative to each other.

Similar to the first embodiment, the control device 3 can acquire information on the road condition ahead in the traveling direction from the communication device 4. Further, when the acquired information indicates the occurrence of an accident, the control device 3 equalizes the driving force distribution ratio to the left and right front wheels 191 and 192 and the left and right rear wheels 193 and 194 before reaching the accident occurrence point. The driving force transmission system 10 is made to perform the preparatory operation for the operation. Specifically, this preparatory operation is an operation of increasing the current supplied to the electromagnetic coil 263 of the driving force transmission device 2 to rotate the propeller shaft 15.

By performing such a preparatory operation before reaching the accident occurrence point, if slip occurs on either the left or right front wheel 191 or 192 at the accident occurrence point, the preparatory operation is not performed. Compared to, it is possible to quickly shift to the four-wheel drive state. This makes it possible to improve the running stability at the accident occurrence point.

(Additional note)
Although the present invention has been described above based on the embodiment, the embodiment does not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be carried out by appropriately modifying it by omitting a part of the configurations or adding or replacing the configurations without departing from the spirit of the present invention.

1,1A ... Four-wheel drive vehicle 10 ... Driving force transmission system 191,192 ... Left and right front wheels 193,194 ... Left and right rear wheels 3 ... Control device 7 ... Ambulance (emergency vehicle)

Claims (2)

A four-wheel drive vehicle having a driving force transmission system capable of distributing the driving force of a driving source to front wheels and rear wheels, and the driving force transmission system is controlled by a control device.
The control device can acquire information on the road condition ahead in the traveling direction, and when the acquired information indicates the occurrence of an accident, the control device drives the front wheels and the rear wheels before reaching the point where the accident occurs. Let the driving force transmission system perform an operation of equalizing the force distribution ratio or a preparatory operation thereof.
Four-wheel drive vehicle. When the acquired information includes information on the stop position of the emergency vehicle, the control device recognizes that an accident has occurred at the stop position.
The four-wheel drive vehicle according to claim 1.

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